1. Field of the Invention
This invention relates to traction structures adapted for securement about the periphery of pneumatic vehicle tires to afford improved traction on slick surfaces.
2. Brief Description of the Prior Art
The ever present problem of providing adequate traction to automobiles under driving conditions where ice and snow cover the roadways has elicited a number of proposed solutions over many years. Generally, such solutions propose the attachment of one or more traction enhancing devices to the pneumatic tires to enable them to bite into or grip slick surfaces more efficiently than the conventional rubber treads carried by the pneumatic tires. Such devices have taken a number of forms, including, as general categories, rubber or synthetic rubber webs which attach to the tire and include some form of straps or belts extending across the tread face of the tire, and metallic traction devices, such as chains, which are secured on the tire and provide sections of chain which extend transversely across the tread face and bite into the ice or snow covering the roadway to afford improved traction.
Chains or metallic antiskid devices have been thought to be most effective and satisfactory in cases where the roadway is covered with a sheet of ice, and the frictional engagement between the roadway and the wheels of the vehicle is poor. The rubber or elastomeric antiskid devices have the advantage over chains and metallic devices in that they do not damage, or cause the wear to, tires upon which they are mounted that such metallic devices cause, and are much quieter in use.
Among the elastomeric types of antiskid devices previously proposed are those which are disclosed in U.S. Pat. Nos. 1,578,803 to Comey, 990,651 to Heer, 4,055,210 to Mongault, 3,770,039 to Pfoertner, 1,932,576 to Dodge, 3,006,397 to Akutowicz and 4,165,774 to Matsui.
The Comey patent proposes to use a pair of flat elastic rings of rubber, or rubber and fabric, which are interconnected by a plurality of crossbars or straps which extend across the tread face of the tire after the rings have been mounted adjacent each of the opposite sidewalls of the tire. The straps are made of the same material as the rings, and both the rings and straps are subject to the normal wear characteristics of rubber, thus undergoing damage and deterioration when subjected to the high stresses induced by high speed driving on rough or nearly dry surfaces.
The type of antiskid device shown in the Heer patent uses inflatable tubular members in annular form as the side members of the device adapted to be positioned adjacent the side walls of the tire. These tubular members are inflatable and are interconnected by cross-pieces which are also tubular. Both the annular side pieces and the cross-pieces are indicated to be made of substantially the same type of materials as are pneumatic tires, and the 1911 date of issuance of this patent would suggest that such material is predominantly rubber, considering the prevalent pneumatic tire construction of that day. For the device to perform in accordance with the invention, it is necessary that the annular tubular side elements of the tire be inflated, and that these side elements be interconnected through buckles and apertured connecting end pieces formed at opposite ends of the tubular side elements.
The antiskid device shown in the Dodge patent is similar to that shown in the Heer and Comey patents, but proposes to use solid rubber or solid rubber having fibrous cores embedded therein in both the side pieces and cross straps. The cross straps are molded integrally with the side pieces.
Matsui U.S. Pat. No. 4,165,774 includes a pair of opposed parallel annular cords which are interconnected by cross belts of molded synthetic resin. Each cross belt is connected at its opposite ends by means of rivets to the cords to retain it in position along the length of the cords. The cords are each solid elements which have some capability of stretching. Neither the wearing properties of the cords or the cross belts are referred to in detail by the patentee.
A generally similar construction is shown in the Pfoertner patent, and the material used in making both the cross straps and side elements is indicated to be polyurethane having a high tensile and tear strength and good abrasion resistance.
In U.S. Pat. No. 4,055,210 to Mongault, the side elements employed for anchoring the cross straps are stainless steel solid or stranded wire, and the cross straps are rubber or other suitable elastic material.
The traction harness shown in Akutowicz U.S. Pat. No. 3,006,397 is constructed entirely of a vulcanizable elastomeric material.